The present invention utilizes the general principles enunciated in U.S. Pat. No. 3,822,410 issued July 2, 1974 to John Madey. Briefly, as explained in detail in that patent, the deflection of the electrons can be achieved either by magnetic or electrical means, for example by a linear array of magnets having opposite polarities, and upon each occurrence of deflection of the individual electron, radiation is emitted. The mechanism can be used to generate a beam of radiation so as to function as an oscillator, or alternatively can be applied to an existent beam, for example of coherent laser light, to effect amplification thereof. As pointed out specifically in that patent, the energy of the electron beam to carry out the process must be quite homogeneous if the operation is to be highly effective, and such a homogeneous electron beam with but a small energy spread is difficult to obtain without very sophisticated and expensive equipment.